1. Field of the Invention
This invention relates to a rolling contact joint useful as a prosthetic knee joint.
2. Description of the Prior Art
Friction and wear have always been problems in conventional joint devices. In addition, such devices have not always provided satisfactory movement, particularly where the necessary movement is complicated and/or exacting, such as, for example, in at least some door hinges and in prosthetic knee joints.
While many joint devices for many different purposes have heretofore been developed and/or utilized, such devices have not been completely successful in all cases where the needed joint has to provide complicated and/or exacting movement. This is particularly true with respect to prosthetic knee joints. In the past, many hinge pin type joints have been proposed for utilization as knee joints, but such joints have met with no more than limited success due, at least in part, to an inability to provide adequate movement to come as near as possible to matching the movement afforded by the healthy human knee and/or to an inability of the joint to withstand the wear and friction resulting from sliding contact at the joint.
Recently, a roller-band device, called a "Rolamite" device, was introduced (see U.S. Pat. No. 3,572,141). This device includes two rollers inside parallel guide surfaces, the rollers being locked in a free-rolling, counterrotating cluster by the elastic constraints of an entwined flexible metallic band under tension. The geometry of this device was said to ensure that the motion of the rollers relative to the guide surfaces is accomplished by rolling and not by sliding, and the resulting device provides basically linear motion of the cluster of rollers.
While such a design as brought out hereinabove might be utilized in some joint applications, it did not completely solve problems in other joint applications, particularly prosthetic knee joint applications. Thus, the need for improved rolling contact joints usable in a variety of applications remained.